The present invention relates to compositions and films made from vinylidene chloride copolymers, especially films suitable for the packaging of pharmaceutical products in blister packs.
The present invention relates to films suitable for making blister packs for pharmaceuticals.
Conventional blister packs typically include a base with one or, more commonly, a plurality of recesses that are surrounded by a shoulder, and a lid attached to the shoulder. Tablets, capsules, or other contents are accommodated in respective recesses, and may be removed therefrom by (1) pressing on the respective recess, thus making the contents penetrate the lid (usually an aluminum foil or the like), or by (2) removing the portion of the lid lying over the recess, thus gaining access to the contents of the recess.
In practice, a base is formed with recesses, and with a shoulder defining the base material in between the recesses; the recesses of the base are filled with tablets, etc.; the base, with the filled recesses, is covered with a lid; and the lid is sealed or otherwise adhered to the shoulder of the base.
The base of the blister pack is sometimes made up of an interior portion (to be adhered to the lid) of ACLAR(trademark) PTFE (polychlorotrifluoroethylene), a material that is very expensive, and with less than optimal oxygen barrier properties. This material displays an MVTR of typically about 0.4 grams/m2. The exterior portion of the base is often a PVC (polyvinyl chloride) of about 250 micrometers (10 mils) thickness. PVC, polyamides, polyolefins, polyesters are other materials which can be used to making the base. An aluminum foil can be added to the base.
The lid is typically made of aluminum foil or an aluminum foil laminate. Aluminum foil is a preferred material for the lids on blister packs as the thickness of the material employed requires relatively little force for it to rupture. Consequently, the energy for penetration is low and the aluminum exhibits essentially no elasticity. Plastic laminates may also be employed for the lid.
Some blister packs feature a lid provided with a line of weakness in the region of each recess. In others, each recess may be covered with an individual lid segment. Within the line of weakness or on each lid segment may be a tab for gripping which enables the individual recess to be exposed by peeling back the lid segment.
Provision of a vinylidene chloride copolymer, often referred to as xe2x80x9csaranxe2x80x9d or xe2x80x9cPVDCxe2x80x9d, in a PVDC composition capable of providing a packaging film with a low moisture vapor transmission rate (MVTR), and preferably also a low oxygen transmission rate (OTR), would be desirable for applications such as the blister packaging of pharmaceutical products sensitive to both oxygen and moisture.
Stabilizers are often used in formulating PVDC-based compositions. These stabilizers reduce the thermal degradation of PVDC formulations during extrusion. Unfortunately, a trade-off in OTR and thermal stability must sometimes be made in designing such formulations. Thus, a composition having increased amounts of a stabilizer will sometimes result in enhanced thermal stability, but at the expense of oxygen barrier properties. Conversely, improved (lower) OTR can be obtained by lowering the relative amounts of stabilizer in the formulation, but this may result in a less stable PVDC composition.
The inventor has produced a composition that provides good moisture vapor and oxygen barrier properties, but without significant loss of thermal stability.
In a first aspect, a polymeric film comprises at least one layer, the at least one layer comprising a vinylidene chloride composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a second aspect, a polymeric film comprises at least one layer, the at least one layer comprising a vinylidene chloride composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a third aspect, a blister pack comprises a base, the base comprising a plurality of recesses, and a shoulder surrounding the recesses; a lid attached to the shoulder; and contents disposed in respective recesses; wherein at least one of the base and lid comprises a vinylidene composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a fourth aspect, a blister pack comprises a base, the base comprising a plurality of recesses, and a shoulder surrounding the recesses; a lid attached to the shoulder; and contents disposed in respective recesses; wherein at least one of the base and lid comprises a vinylidene composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a fifth aspect, a vinylidene chloride composition comprises 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a sixth aspect, a vinylidene chloride composition comprises 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
Definitions
xe2x80x9c(meth)acrylic acidxe2x80x9d herein refers to both acrylic acid and/or methacrylic acid;
xe2x80x9c(meth)acrylatexe2x80x9d herein refers to both acrylate and methacrylate;
xe2x80x9cpolymerxe2x80x9d herein refers to the product of a polymerization reaction, and is inclusive of homopolymers, copolymers, terpolymers, tetrapolymers, etc.;
xe2x80x9ccopolymerxe2x80x9d herein refers to a polymer formed by the polymerization reaction of at least two different monomers and is inclusive of random copolymers, block copolymers, graft copolymers, etc.;
xe2x80x9cethylene/alpha-olefin copolymerxe2x80x9d (EAO) herein refers to copolymers of ethylene with one or more comonomers selected from C3 to C10 alpha-olefins such as propene, butene-1,hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long polymer chains with relatively few side chain branches arising from the alpha-olefin which was reacted with ethylene. This molecular structure is to be contrasted with conventional high pressure low or medium density polyethylenes which are highly branched with respect to EAOs and which high pressure polyethylenes contain both long chain and short chain branches. EAO includes such heterogeneous materials as linear medium density polyethylene (LMDPE), linear low density polyethylene (LLDPE), and very low and ultra low density polyethylene (VLDPE and ULDPE), such as DOWLEX(trademark) or ATTANET(trademark) resins supplied by Dow, ESCORENET(trademark) or EXCEED(trademark) resins supplied by Exxon; as well as linear homogeneous ethylene/alpha olefin copolymers (HEAO) such as TAFMER(trademark) resins supplied by Mitsui Petrochemical Corporation, EXACT(trademark) resins supplied by Exxon, or long chain branched (HEAO) AFFINITY(trademark) resins supplied by the Dow Chemical Company, or ENGAGE(trademark) resins supplied by DuPont Dow Elastomers;
xe2x80x9cpackagexe2x80x9d herein refers to a film configured around a product;
xe2x80x9cfilmxe2x80x9d herein refers to plastic web materials having a thickness of 0.50 mm (20 mils) or less such as 0.25 mm (10 mils) or less;
xe2x80x9cseal layerxe2x80x9d herein refers to a layer of a film that can be involved in the sealing of the film to itself or another layer;
xe2x80x9csealxe2x80x9d herein refers to a bonding of a first film surface to a second film surface created by heating (e.g., by means of a heated bar, hot air, infrared radiation, ultrasonic sealing, etc.) the respective surfaces to at least their respective seal initiation temperatures;
xe2x80x9cbarrierxe2x80x9d herein refers to a layer of a film that can significantly retard the transmission of one or more gases (e.g., O2);
xe2x80x9cabuse layerxe2x80x9d herein refers to a layer of a film that can resist abrasion, puncture, and/or other potential causes of reduction of package integrity, and/or potential causes of reduction of package appearance quality;
xe2x80x9ctie layerxe2x80x9d herein refers to a layer of a film that can provide interlayer adhesion to adjacent layers that include otherwise nonadhering or weakly adhering polymers;
xe2x80x9cbulk layerxe2x80x9d herein refers to a layer of a film that can increase the abuse resistance, toughness, or modulus of a film;
xe2x80x9claminationxe2x80x9d herein refers to the bonding of two or more film layers to each other, e.g. by the use of polyurethane adhesive;
xe2x80x9ctotal free shrinkxe2x80x9d means the percent dimensional change in a 10 cmxc3x9710 cm specimen of film, when shrunk at a specified test temperature such as 85xc2x0 C. (185xc2x0 F.), with the quantitative determination being carried out according to ASTM D 2732, as set forth in the 1990 Annual Book of ASTM Standards, vol. 08.02, 368-371, the entire disclosure of which is incorporated herein by reference. xe2x80x9cTotal free shrinkxe2x80x9d refers to the totality of the free shrink in both the longitudinal direction and the transverse direction.
xe2x80x9cmachine directionxe2x80x9d herein refers to the direction along the length of a film, i.e., in the direction of the film as it is formed during extrusion and/or coating; and
xe2x80x9ctransverse directionxe2x80x9d herein refers to the direction across a film, i.e., the direction that is perpendicular to the machine direction.
xe2x80x9cLinear low density polyethylenexe2x80x9d (LLDPE) herein refers to polyethylene having a density between 0.917 and 0.925 grams per cubic centimeter, made by Zeigler/Natta catalysis.
xe2x80x9cLinear medium density polyethylenexe2x80x9d (LMDPE) herein refers to polyethylene having a density between 0.926 grams per cubic centimeter and 0.939 grams per cubic centimeter, made by Zeigler/Natta catalysis.
The term xe2x80x9corientation ratioxe2x80x9d (i.e., the product of the extent to which a film is oriented in several directions, usually two directions perpendicular to one another) is used when describing the degree of orientation of a given film. Orientation in the machine direction is referred to as xe2x80x9cdrawingxe2x80x9d, whereas orientation in the transverse direction is referred to as xe2x80x9cstretchingxe2x80x9d. For films extruded through an annular die, stretching is obtained by blowing the film to produce a bubble. For such films, drawing is obtained by passing the film through two sets of powered nip rolls, with the downstream set having a higher surface speed than the upstream set, with the resulting draw ratio being the surface speed of the downstream set of nip rolls divided by the surface speed of the upstream set of nip rolls.
All compositional percentages used herein are presented on a xe2x80x9cby weightxe2x80x9d basis, unless designated otherwise.